Means for producing pipe fittings



Nov. 4, 1958 i w. P. HILL 2,858,787

MEANS FOR PRODUCING PIPE FITTINGS Filed May 28, 1956 '1! 1/! I III/ IN V EN TOR.

din/174st United States Patent ,MEANS FOR PRODUCING PIPE FITTINGS Walter P. Hill, Detroit, Mich.

Application May 28, 1956, Serial No. 587,674

" 1 Claim. (c1.113-.44

This invention relates to metal working, and more particularly to an improved method and apparatus for forming tubular branch fittings, such as T-fittings, L-fittings, cross fittings or the like. V

In the past, many methods have been devised for forming such fittings from a tubular blank wherein the blank is placed in a die and subjected to the combined forces of pressurized filler material within the blank and compression on the ends of the blank, which forces cause the metal to flow and form a desired tubular branch fitting. In such processes, the volume of the finished fitting is lessthan the volume of the original blank, which, of course, is due, at least in part, to the fact that the walls of the finished fitting are thicker than the walls of the tubular blank.

In so forming branch fittings, it is necessary that the rate of displacement ofthe filler material be kept in balance with the rate of change i in the volume of the blank during the working operation, and in view of the reduction in the volume of the fitting. In Patent No. 2,735,389 issued February 21, 1956, a method and apparatus are disclosed for so forming fittings, and in the apparatus of this patent the filler material is formed from a preformed slug of filler material having an aperture or apertures formed therein so that as the filler material flows to extrude a lateral branch, the void or aperture in the metal slug or filler material will gradually fill. As the volume of the void or aperture in the slug is equal to the difference in the volume of the tubular blank and the finished fitting, the fitting can be formed without bursting the walls thereof.

There are certain disadvantages to the apparatus disclosed in the abovementioned patent. In the first place, it isnecessary to drill or otherwise form the apertures or voids in the filler material slugs. Secondly, with the apparatus shown in this patent, there is considerable waste material in the lateral branch because of the way the branch is formed, and still further, the method and apparatus disclosed in the aforesaid patent requires the use of tubular blanks having heavier walls than are necessary.

-It is, therefore, an object of this invention to provide apparatus for forming tubular branch fittings of the aforementioned type wherein a solid slug of filler material is employed, which slug need not be provided with aper-- tures or voids, thus reducing the cost of producing the fittings.

It is a still further object of this invention to provide M an improved apparatus for'forming fittings of the aforementioned type in which means are provided in the forming tools for accommodating the excess volume of the filler material which must be released because of the diminution of the volume of the tubular blank during the forming operation.

,It is a still furtheriobject of this invention to provide in an apparatus of the aforementioned type, an improved arrangement to reduce scrap or material losses when a tubular blank is formed into a branch-type fitting, and to permit the use of a tubular blank having a thinner wall than has been heretoforepossible.

-It isa still further object of this invention to provide apparatus of the aforementioned type which will form a 2,858,787 Patented Nov. 4, 1958 lateral branch of the fitting is more uniform and is heavier than has been heretofore possible.

It is a still further object of this invention to provide an apparatus of the aforementioned type which will produce better branch-type tubular fittings than any heretofore known, in a faster, simpler and more economical manner than has heretofore been possible.

These and other objects of this invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawing, in which:

Figure 1 is a fragmentary, longitudinal, sectional view of a tubular blank and apparatus for forming the same into a branch-type fitting, with the parts being shown at the beginning of the metal working operation;

Fig. 2 is a view similar to Fig. 1, illustrating the position of the parts at the completion of the metal working operation; and

Fig. 3 is an enlarged longitudinal, sectional view of a branch-type tubular fitting with the forming plungers shown adjacent thereto.

Referring now to the drawing, it will be seen that apparatus is illustrated for forming a T-shaped fitting 5 from a cylindrical tubular blank 7. It will, however, be understood that other types of branch fittings may be formed without departing from the scope of this invention. It will, furthermore, be appreciated that the material of the blank may vary, but in the particular illustration, the tubular blank 7 is formed of copper.

The tubular blank 7 is placed in a die 9 which may be of a conventional two-piece type. The two die sections provided a main cylindrical passageway 11 of a size to properly receive the tubular blank 7. Passageway 11 extends through the die so that plungers 13 and 13' may extend from opposite sides of the die into engagement with the tubular blank, and a slug 15 of filler material disposed therein. The die is provided with a branch passage 17 into which material from the blank 7 is extruded to form the branch-type fitting 5. The slug 15 may be formed of any suitable incompressible, flowable, low melting point metal, and preferably is formed of a lead and bismuth alloy which is soluble in oil and will melt at a temperature above 212 and in the order of 260 to 270. The slug 15 is a solid cylindrical slug which is of a diameter such that it may be slipped into the interior of the tubular blank 7. Preferably, the di ameter of the slug is as large as possible, which still permitting easy insertion of the slug into the tubular blank. The volume of the slug 15 exceeds the volume of the lateral branch of the fitting 5, and is such that during the metal working operation, the branch will be filled with the slug or filler material 15, as well as the portion of the main passage of the fitting, as can be seen in Fig. 2.

v In the instant embodiment, the tubular blank, in its initial form, is approximately 2% inches long, while the slug is approximately 1%; inches long. The inner ends of the plungers 13 and 13 are of a diameter such that they may slide into the tubular blank 7, in generally borefitting engagement, so as to abut the opposite ends of the slug 15, as illustrated in Fig. 1. A shoulder 19 is providedon each plunger, and the shoulders are adapted to engage the opposite ends of the tubular blank 7. The

I intosnug engagement with the wall of the blank.

branch fitting'in which the thickness of the wall ofthe The volume of the tubular blank 7 in its initial un-.

Worked form is greater than the volume of the fitting 5 in its finished form. This results from the fact that the walls of the finished fitting are heavier than the walls of the tubular blank, and from the fact that a certain portion of the metal of the tubular blank forms an end wall 23 at the remote end of the fitting lateral branch 25. The combined volumes of the cavities 21 are substantially equal to the difference between the volume of the tubular blank 7 and the volume of the finished fitting 5. The volume of the cavities 21 might exceed this difference in volume slightly, but should be at least as great as the difference in the volumes of the metal part.

When it is desired to form the fitting, the tubular blank with the slug therein is placed in the die 9 and the die is closed. The plungers 13 and 13' are then moved into the die by suitable actuating means, such as fluid-operated mechanisms. When the movement of the plungers toward each other has caused the filler material of the slug 15 to flow into substantial engagement with the wall of the tubular blank throughout the axial extent or length of the slug, the shoulders 19 on the plungers will engage the opposite ends of the tubular blank 7. Thereafter, continued movement of the plungers 13 and 13' toward each other will cause the filler material to extrude the wall of the tubular blank into the die passageway 17. In view of the fact that the tube is being shortened in length during the application of the compressive forces to the slug 15, the extrusion of the lateral branch 25 will occur without bursting the fitting. It will be noted that the remote end of the die passageway 17 is closed by an end wall 27 so that the end wall 23 of the fitting branch 25 will be substantially fiat and can be cut oh so as to provide an open fitting after the metal working operation, with a minimum of scrap or loss of metal. Furthermore, with such an arrangement, the fiow of the metal into the lateral die passage 17 is dammed up; thus the lateral branch will have a heavier wall than in cases where the passageway 17 is open and not closed. Still further, such an arrangement permits the use of a lighter wall tubular blank and permits the formation of a fitting in which the wall 25 of the lateral branch will be uniform in thickness, and any undue gathering of the copper adjacent the center part of the main passageway is eliminated.

When the plungers move toward each other and cause the filler material to start extruding the tubular blank into the passage 17, less pressure will be required than toward the end of the extruding operation. Therefore, upon the application of initial pressures of the order of 30,000 pounds, the filler material of the slug 15 will cause a portion of the tubular blank to extrude into the passage 17 to about the position illustrated by the dot-dash line 29, while the slug material will flow into the plunger cavities to about the position shown by the dot-dash line 31. In view of the fact that it requires greater pressure to further extrude the lateral branch 25, because the tensile strength of the material goes up as it is worked, the crosssectional areas of the plunger cavities 21 are reduced as they extend into the plungers. By way of example, it may require an increase in pressure of from about- 30,000 pounds to about 60,000 pounds to extrude a portion of the tubular blank into the passageway 17 from the position illustrated by the dot-dash line 29 to the position of the end wall 23. Therefore, the pressure requirements to extrude the lateral branch substantially double. In a similar manner, the cross-sectional areaof the cavities 21 are proportionately reduced so that the cross-sectional area at the back of each cavity 21 is substantially one-half the cross-sectional area at the slug-engaging end of the plungers. Thus, a proper balance between the flow of the filler material into the cavities 21 and the extrusion of the lateral branch 25 will occur during the metal working'operation without reaching the bursting point of the metal.

In view of the fact that the slug 15 of filler material is a solid slug, it does not need to be drilled or otherwise formed with apertures or voids therein, and the cost of producing each fitting is thus materially reduced. That is, with the tapered cavities provided in the plungers, there is no necessity of providing any voids or apertures in the slug, and the plungers may be used over and over again, while a new slug must be used eachtime a fitting is formed. Furthermore, in view of the fact that the cavities 21 are tapered or of a frusto-conical shape, the filler material, which is in the cavities at the end of each metal working operation, maybe easily removed.

After the metal working operation has been completed in the die 9, the filler material is melted out of the fitting and the plungers, and the end wall 23 is cut from the fitting to provide a branch-type fitting which is made in a relatively inexpensive manner having a consistent and uniform wall thickness.

What is claimed is:

Apparatus for forming a branch fitting such as a T or the like by extruding at least one lateral branch outwardly from a tubular blank which has a greater volume than the finished fitting, including a die having a main passage adapted to receive the tubular blank and a lateral branch passage into which the fitting branch is extruded, the end of said branch passage remote from said main passage being closed by a substantially fiat end wall, a solid slug of an incompressible, flowable, low melting point metal disposed in said tubular blank and having its opposite ends spaced from the opposite ends of the tubular blank.

and substantially filling the interior of the blank throughout the axial extent of the slug, the volume of said slug being greater than the volume of the lateral branch to be formed in the fitting, oppositely acting plungers receivable in the opposite ends of the blank and each having an end engageable with the opposite ends of the slug, each of said plungers having a shoulder spaced from said plunger end which engages one end of the blank after said plungers have engaged said slug and caused the same to firmly en gage the wall of the blank, the slug-engaging end of each of said plungers having an opening therein extending inwardly into said plunger, the cross-sectional area of said opening being greater adjacent the slug-engaging end than adjacent the opposite end thereof, the volume of said plunger openings being substantially equal to the difference between the volume of the blank and the volume of the finished fitting, the cross-sectional area of each of said.

openings adjacent the slug-engaging end thereof being substantially twice the cross-sectional area of each opening adjacent the opposite end thereof, and means for forcibly moving said plungers toward each other so as to simultaneously cause the material of said slug to force the wall of the tubular blank into the die lateral branch while compressing the opposite ends of the blank and thus providing a fitting lateral branch which is closed at its remote end by a substantially fiat end wall whereby the branch fitting is completely formed with relief only being provided for said difference between the volume of the blank and the volume of the finished fitting and with no provision being made for pressure relief.

References Cited inv the file of this patent UNITED STATES PATENTS 2,027,285 Parker Jan. 7, 1936 2,557,403 Abrogast June 19, 1951 2,735,389 Wurzburger Feb. 21, 1956 2,762,326 Burkhart Sept.- 11, 1956 

